Sesquiterpene lactone glycosides from Arnica longifolia.

Flowers of ARNICA LONGIFOLIA were investigated for the occurrence of sesquiterpene lactone glycosides. A mixture containing the two isomeric 11alpha,13-dihydro- and 11beta,13-dihydro-4 H-tomentosin glucosides, previously isolated from A. AMPLEXICAULIS and A. MOLLIS, together with the two isomeric 11alpha,13-dihydro- and 11beta,13-dihydro-4 H-carabrone glucosides were found in A. LONGIFOLIA. All carbon and proton shifts of the glycosides could be assigned by their 2D-COSY and 2D-HETCOR spectra and spectroscopy of their respective aglycones, obtained via enzymatic hydrolysis.